/oss/taxonomy/term/737/all en /oss/article/did-you-know-general-science/when-science-allows-you-lose-your-head <hr /> <p><em>This article was first published in <a href="https://montrealgazette.com/opinion/columnists/the-right-chemistry-when-science-allows-you-to-lose-your-head">The Montreal Gazette.</a></em></p> Fri, 18 Oct 2024 20:01:39 +0000 Joe Schwarcz PhD 10121 at /oss /oss/article/you-asked/what-fluorescence <p style="text-align:justify"><a href="http://blogs.mcgill.ca/oss/?attachment_id=3171" rel="attachment wp-att-3171"><img alt="cells" height="150" src="http://blogs.mcgill.ca/oss/files/2012/11/FluorescentCells-150x150.jpg" width="150" /></a>Fluorescence is the ability of certain chemicals to give off visible light after absorbing radiation which is not normally visible, such as ultaviolet light. This property has led to a variety of uses. Let's shed some further light on this topic; consider the omnipresent "fluorescent" lights. Just how do they work? Fluorescent tubes contain a small amount of mercury vapor. The application of an electric current causes a stream of electrons to traverse the tube. These collide with the mercury atoms which become energized and consequently emit ultraviolet light. The inside of the tube is coated with a fluorescent material, such as calcium chlorophosphate, which converts the invisible ultraviolet light into visible light. The same idea is used to produce color television pictures. The screen is coated with tiny dots of substances which fluoresce in different colors when they are excited by a beam of electrons which is used to scan the picture.</p> <p><a href="http://blogs.mcgill.ca/oss/2012/11/15/what-is-fluorescence/">Read more</a></p> Fri, 16 Nov 2012 03:15:58 +0000 Joe Schwarcz PhD 1791 at /oss